Boiler SNCR denitration control method and system capable of automatically adjusting ammonia spraying

Abstract

The invention discloses a boiler SNCR denitration control method and system capable of automatically adjusting ammonia injection, and relates to the technical field of boiler denitration, the system comprises a reducing agent supply unit, a multi-stage injection unit, a temperature monitoring network, a flue gas analysis monitoring module and a control unit; the reducing agent supply unit consists of a urea solution storage tank, a high-pressure conveying module and a parallel filtering branch; the multi-stage spraying unit comprises a plurality of layers of atomizing spray gun arrays; the temperature monitoring network is provided with a plurality of groups of thermoelectric couples; by means of the control system and the control method, the temperature of flue gas in the boiler can be monitored in real time, opening and closing of the atomization spray gun are controlled through the control system according to the temperature of the flue gas, accurate matching of the ammonia spraying amount is achieved, the denitration efficiency condition is monitored in real time, waste of urea solution consumption is avoided, and the denitration raw material cost is reduced; automatic ammonia spraying adjustment of the boiler SNCR denitration system is achieved, and the situation that the operation cost is increased due to over-spraying of a urea solution is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of boiler denitration, and in particular relates to a boiler SNCR denitration control method and system with automatic adjustment of ammonia injection. Background Art

[0002] A boiler is an energy conversion device that heats water into steam, high-temperature water or organic heat carriers by burning fuel (such as coal, natural gas, oil) or other energy sources (such as electricity, waste heat), providing heat energy for industrial production and daily life. Its core consists of two parts: the "pot" (the pressurized component that holds water and steam) and the "furnace" (the place where the fuel is burned). SNCR technology reduces NOx in flue gas into harmless nitrogen and water by injecting an amino-containing reducing agent into a specific temperature window in the boiler furnace. With the continuous improvement of national environmental protection standards, the environmental pressure faced by boilers is increasing. The flue gas commonly used in industry is The main flue gas denitrification technologies are SCR flue gas denitrification and SNCR flue gas denitrification. The main principle of SNCR flue gas denitrification technology is to spray urea solution or ammonia water as a reducing agent into the flue gas at 850-1150℃ without the action of a catalyst. The reducing agent undergoes an oxidation-reduction reaction with NOx in the flue gas at high temperature to generate N2, thereby achieving NOx removal. It has the advantages of small footprint, small investment, low operating cost, simple system and little impact on boiler operation. The main reaction of urea as a reducing agent is: 4NO+2(NH2)2CO+O2→4N2+2CO2+4H2O.

[0003] When the boiler SNCR denitrification process is in use, urea, as a reducing agent, reacts with NOx in the flue gas under certain temperature conditions. However, the flue gas temperature in the boiler is uneven, and the flue gas temperature at the urea spray gun position is often too low. At this time, the urea cannot react with the NOx in the flue gas, causing the problem of NOx overspray. On the one hand, it causes waste of raw materials and increases operating costs; on the other hand, the exhaust ammonia escape detection is prone to exceed the standard and cannot meet people's needs. Summary of the Invention

[0004] The present invention aims to solve the technical problems existing in the prior art; to this end, the present invention proposes a boiler SNCR denitration control method and system with automatic adjustment of ammonia injection.

[0005] A boiler SNCR denitrification control method and system with automatically adjusted ammonia injection comprises a reducing agent supply unit, a multi-stage injection unit, a temperature monitoring network, a flue gas analysis and monitoring module, and a control unit. The reducing agent supply unit comprises a urea solution storage tank, a high-pressure delivery module, and a parallel filter branch, and the urea solution concentration is controlled within the range of 10-20%. The multi-stage injection unit comprises an array of several layers of atomizing spray guns arranged axially along the boiler flue, with each layer provided with more than four dual-fluid spray guns, and the spray coverage area is ≥85% of the flue cross-section. The temperature monitoring network is configured with several groups of thermocouples mounted on the dual-fluid spray guns, with a sampling frequency of ≥3 times / second. The flue gas analysis and monitoring module comprises several groups of NOx concentration detection instruments arranged inside the boiler, which detect the inlet / outlet NOx concentration and ammonia escape in real time. The control unit comprises a temperature field prediction module and a dynamic injection algorithm, and interacts with the DCS system data via the OPC protocol.

[0006] As a further solution of the present invention, the control unit integrates real-time data from the temperature monitoring network and the flue gas analysis and monitoring module via the OPC protocol to dynamically adjust the operating parameters of the reductant supply unit and the multi-stage injection unit (including the dual-fluid spray gun atomization parameters). For example, when the temperature field prediction model (LSTM neural network) predicts that the temperature in a certain area will drop to 850°C, the spray gun in that area is immediately shut down and the adjacent upper-layer compensatory injection is activated. The reductant supply unit's high-pressure pump delivers a urea solution with a concentration of 10-20% to the multi-stage injection unit via a parallel filter branch. When the flue gas analysis and monitoring module detects that the outlet NOx concentration exceeds the standard, the redundant spray gun group is automatically activated and the atomization angle is adjusted to increase the coverage area to 85% of the flue cross-section.

[0007] As a further solution of the present invention, the high-pressure delivery module includes a high-pressure delivery pump and a urea solution delivery pipeline that sequentially connects a urea solution storage tank, a parallel filter branch, and a dual-fluid spray gun; the urea solution delivery pipeline is provided with an electric heating module, and the heating temperature is controlled at 40-60°C to prevent urea crystals from clogging the pipeline.

[0008] As a further solution of the present invention: the parallel filter branch includes several stages of filter structures; the filter structure includes a stainless steel filter screen and a self-cleaning device; the self-cleaning device adopts a backwash structure and is monitored in real time by a pressure differential sensor; when the pressure difference of the parallel filter branch is ≥0.15MPa, the backwash structure is started and the flushing cycle is ≤10 minutes.

[0009] As a further solution of the present invention: the compressed air pressure of the dual-fluid spray gun is 0.35-0.45 MPa, the urea solution pressure is 0.18-0.22 MPa, the atomization angle is 60-90°, and the atomized particle size distribution D90≤50 μm; the thermocouple is a K-type armored thermocouple or an S-type thermocouple, and the installation spacing of the thermocouple is set to 0.8±0.2m at the front end of the dual-fluid spray gun, and the furnace temperature at the spray gun position is detected in real time, and the temperature detection range is 800-1100°C.

[0010] As a further solution of the present invention: the temperature monitoring network includes dividing the boiler into several groups of longitudinal temperature zones at different locations inside the boiler, and dynamically adjusting the zone range according to the SNCR optimal reaction temperature window; installing a dual-fluid spray gun and a thermocouple at different longitudinal temperature zones, monitoring the temperature gradient of the longitudinal cross-section of the furnace in real time, and dynamically adjusting the spray gun flow rate according to the real-time temperature value; the number of the longitudinal temperature zones is set to 3-5, and the zone range is dynamically adjusted according to the SNCR optimal reaction temperature window (850-1100°C).

[0011] For example: high temperature zone (900-1100℃): located in the upper part of the furnace, where the main spray gun group is arranged; medium temperature zone (850-950℃): located in the middle of the furnace, used for compensatory spraying during temperature fluctuations; low temperature zone (800-850℃): selectively enabled only under special working conditions (such as load drop).

[0012] As a further solution of the present invention: the NOx concentration detection instrument is set 1-3 meters downstream of each dual-fluid spray gun, and the NOx concentration detection instrument is connected to the control unit to provide real-time feedback on the local denitrification efficiency; when the local denitrification efficiency is lower than 80%, the atomization pressure and injection angle of the corresponding dual-fluid spray gun are adjusted first, and the coordinated compensatory injection of adjacent spray guns is triggered.

[0013] As a further solution of the present invention: the temperature field prediction module adopts an LSTM neural network model, and the input parameters include boiler load rate, burnout damper opening, and coal powder calorific value, and outputs a temperature distribution thermodynamic map for the next 15 minutes.

[0014] As a further solution of the present invention: the dynamic injection algorithm is based on the PID control principle and adopts an injection control strategy of a stratified compensation mechanism and redundant injection logic; the stratified compensation mechanism: when the temperature of a layer is lower than 860°C, the spray gun of that layer is closed and the adjacent upper layer is activated; the redundant injection logic: when the outlet NOx concentration is greater than 50mg / m³, the standby spray gun group is started, and the compressed air pressure is automatically increased to 0.45MPa; the temperature field prediction module pushes the temperature field distribution tensor to the dynamic injection algorithm every 10 seconds as an input parameter for injection angle / depth adjustment; the dynamic injection algorithm provides real-time feedback of the actual denitrification efficiency to the prediction module for online fine-tuning of the LSTM model.

[0015] As a further solution of the present invention: a boiler SNCR denitrification control method with automatic adjustment of ammonia injection, the specific steps are as follows: Step A: transporting the urea solution in the urea solution storage tank to the multi-stage injection unit; Step B: obtaining temperature data at the spray gun position by arranging a thermocouple at the front end of the dual-fluid spray gun; Step C: Obtain the NOx concentration value in the flue gas in real time through the NOx concentration detection instrument and feed the value back to the control unit; Step D: The control unit dynamically adjusts the compressed air pressure, atomization angle, and urea solution injection volume of the dual-fluid spray gun according to the NOx concentration; Step E: Monitor the ammonia escape in real time using a NOx concentration detection instrument. When the escape is ≥5ppm, adjust the total flow rate of the spray gun and the ammonia injection position.

[0016] As a further solution of the present invention: the control unit dynamically calculates the demand for urea solution based on a multivariable collaborative control algorithm by collecting data on inlet NOx concentration, outlet NOx concentration, ammonia escape concentration, flue gas volume and oxygen content in real time; at the same time, combined with the temperature detection data of the thermocouple 5 installed in the furnace at each spray gun, the boiler is divided into 3-5 longitudinal temperature zones, and the spray gun opening strategy is dynamically adjusted according to the following rules; when the temperature of a certain zone is between 850-1100°C and the NOx concentration in the corresponding area is higher than the set threshold, the spray gun in the zone is activated and 60-80% of the urea demand is allocated; if the temperature difference between adjacent zones exceeds ±50°C, the spray gun position balancing module is started, the dual-fluid spray gun in the high-temperature zone is preferentially enabled and the dual-fluid spray gun in the low-temperature zone is closed; when the ammonia escape concentration exceeds 3ppm, the total flow rate of the currently working spray gun is proportionally reduced by 10-30%, and the spray gun is redistributed. The system is divided into zones from the ammonia position to those with an oxygen content ≥4%; multiple parameters such as inlet / outlet NOx, ammonia slip, flue gas volume, and oxygen content are integrated to build a closed-loop feedback control logic; the relationship between the algorithm input variables (inlet / outlet concentration, etc.) and the output control quantity (urea demand) is clarified; the temperature zones are divided vertically (3-5 zones) and the thermocouple data is combined to achieve precise spatial control; the temperature threshold (850-1100°C) is set in conjunction with the concentration threshold to ensure that the spray gun operates only in the effective reaction window; the urea amount distribution ratio (60-80%) of the zones is optimized for reaction efficiency and to avoid local overspray; when the temperature difference exceeds the limit, the spray gun balancing module is triggered, giving priority to the high-temperature zone to improve the denitrification efficiency (refer to the optimal reaction temperature of SNCR); the ammonia slip concentration threshold is set (3ppm), and when it exceeds the limit, the amount is reduced by a gradient (10-30%) and the ammonia spray position is moved to the high-oxygen zone (≥4%) to inhibit the formation of ammonium bisulfate.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention can monitor the flue gas temperature in the boiler in real time through the control system and control method set up. The opening and closing of the atomizing spray gun is controlled by the control system according to the flue gas temperature, and the ammonia spraying amount is accurately matched, thereby realizing real-time monitoring of the denitrification efficiency, avoiding the waste of urea solution consumption, reducing the cost of denitrification raw materials, improving the denitrification reaction efficiency, realizing the automatic adjustment of ammonia spraying by the boiler SNCR denitrification system, avoiding the overspray of urea solution and increasing the operating cost, and accurately calculating the demand for urea solution through the adjustment of the automatic control system, and dynamically adjusting the number and position of the spray guns opened by temperature zoning the temperature in the furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural diagram of the control system of the present invention.

[0019] Figure 2 Flowchart of the control method of the present invention.

[0020] In the figure: 1. Urea solution storage tank; 2. High-pressure transmission module; 3. Parallel filter branch; 4. Dual-fluid spray gun; 5. Thermocouple; 6. Economizer; 7. Air preheater. DETAILED DESCRIPTION

[0021] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] Example 1 See also Figure 1-2 The present application provides a boiler SNCR denitrification control method and system with automatic adjustment of ammonia injection, including a reducing agent supply unit, a multi-stage injection unit, a temperature monitoring network, a flue gas analysis and monitoring module and a control unit; the reducing agent supply unit is composed of a urea solution storage tank 1, a high-pressure delivery module 2, and a parallel filter branch 3, and the urea solution concentration is controlled in the range of 10-20%; the multi-stage injection unit includes several layers of atomizing spray gun arrays arranged axially along the boiler flue, each layer is provided with more than 4 dual-fluid spray guns 4, and the spray coverage area is ≥85% of the flue cross-section; the temperature monitoring network is configured with several groups of thermocouples 5 installed on the dual-fluid spray guns 4, with a sampling frequency of ≥3 times / second; the flue gas analysis and monitoring module includes several groups of NOx concentration detection instruments arranged inside the boiler, which detect the inlet / outlet NOx concentration and ammonia escape in real time; the control unit includes a temperature field prediction module and a dynamic injection algorithm, and exchanges data with the DCS system through the OPC protocol.

[0023] The boiler is provided with an economizer 6 and an air preheater 7. One end of the air preheater 7 can introduce air into the boiler, and the air outlet of the air preheater 7 can be connected to an external dust removal system.

[0024] The control unit integrates real-time data from the temperature monitoring network and flue gas analysis and monitoring modules via the OPC protocol to dynamically adjust the operating parameters of the reductant supply unit and the multi-stage injection unit (the atomization parameters of the dual-fluid spray gun 4). For example, if the temperature field prediction model (LSTM neural network) predicts that the temperature in a certain area will drop to 850°C, the spray gun in that area will be immediately shut down and the adjacent upper layer compensation injection will be activated; The high-pressure pump of the reducing agent supply unit delivers a urea solution with a concentration of 10-20% to the multi-stage injection unit through the parallel filter branch 3; when the flue gas analysis and monitoring module detects that the outlet NOx concentration exceeds the standard, the redundant spray gun group is automatically activated and the coverage area is increased to 85% of the flue cross-section by adjusting the atomization angle.

[0025] The high-pressure delivery module 2 includes a high-pressure delivery pump and a urea solution delivery pipeline that sequentially connects the urea solution storage tank 1, the parallel filter branch 3, and the dual-fluid spray gun 4. The urea solution delivery pipeline is provided with an electric heating module, and the heating temperature is controlled at 40-60°C to prevent urea crystals from clogging the pipeline.

[0026] The parallel filter branch 3 includes several stages of filter structures; the filter structure includes a stainless steel filter screen and a self-cleaning device; the self-cleaning device adopts a backwash structure and is monitored in real time by a pressure differential sensor; when the pressure differential of the parallel filter branch 3 is ≥0.15MPa, the backwash structure is started and the flushing cycle is ≤10 minutes.

[0027] The compressed air pressure of the dual-fluid spray gun 4 is 0.35-0.45 MPa, the urea solution pressure is 0.18-0.22 MPa, the atomization angle is 60-90°, and the atomized particle size distribution D90≤50 μm; the thermocouple 5 uses a K-type armored thermocouple or an S-type thermocouple, and the installation spacing of the thermocouple 5 is set to 0.8±0.2m at the front end of the dual-fluid spray gun 4, and the furnace temperature at the spray gun position is detected in real time, and the temperature detection range is 800-1100°C.

[0028] The temperature monitoring network includes dividing the boiler into a plurality of longitudinal temperature zones at different locations inside the boiler, and dynamically adjusting the zone range according to the SNCR optimal reaction temperature window; The dual-fluid spray gun 4 and the thermocouple 5 are installed in different longitudinal temperature zones to monitor the temperature gradient of the longitudinal section of the furnace in real time and dynamically adjust the spray gun flow rate according to the real-time temperature value; the number of the longitudinal temperature zones is set to 3-5, and the zone range is dynamically adjusted according to the SNCR optimal reaction temperature window (850-1100℃).

[0029] For example: high temperature zone (900-1100℃): located in the upper part of the furnace, where the main spray gun group is arranged; medium temperature zone (850-950℃): located in the middle of the furnace, used for compensatory spraying during temperature fluctuations; low temperature zone (800-850℃): selectively enabled only under special working conditions (such as load drop).

[0030] The NOx concentration detection instrument is arranged 1-3 meters downstream of each dual-fluid spray gun (4). The NOx concentration detection instrument is connected to the control unit to provide real-time feedback on the local denitrification efficiency. When the local denitrification efficiency is lower than 80%, the atomization pressure and injection angle of the corresponding dual-fluid spray gun 4 are adjusted first, and the coordinated compensation injection of the adjacent spray guns is triggered.

[0031] The temperature field prediction module adopts an LSTM neural network model, and its input parameters include boiler load rate, burnout damper opening, and calorific value of pulverized coal, and outputs a thermodynamic map of temperature distribution in the next 15 minutes.

[0032] The dynamic injection algorithm is based on the PID control principle and adopts an injection control strategy with a stratified compensation mechanism and redundant injection logic. The stratified compensation mechanism: when the temperature of a layer is lower than 860°C, the spray gun of that layer is shut down and the adjacent upper layer is activated. The redundant injection logic: when the outlet NOx concentration is greater than 50mg / m³, the backup spray gun group is activated and the compressed air pressure is automatically increased to 0.45MPa. The temperature field prediction module pushes the temperature field distribution tensor to the dynamic injection algorithm every 10 seconds as an input parameter for injection angle / depth adjustment. The dynamic injection algorithm provides real-time feedback of the actual denitrification efficiency to the prediction module for online fine-tuning of the LSTM model.

[0033] Example 2 Reference Figure 2 , which is the second embodiment of the present invention, wherein the present invention is a boiler SNCR denitrification control method with automatic adjustment of ammonia injection, the specific steps are as follows: Step A: transporting the urea solution in the urea solution storage tank 1 to the multi-stage injection unit; Step B: obtaining temperature data of the spray gun position by means of a thermocouple 5 arranged at the front end of the dual-fluid spray gun 4; Step C: Obtain the NOx concentration value in the flue gas in real time through the NOx concentration detection instrument and feed the value back to the control unit; Step D: The control unit dynamically adjusts the compressed air pressure, atomization angle and urea solution injection amount of the dual-fluid spray gun 4 according to the NOx concentration; Step E: Monitor the ammonia escape in real time using a NOx concentration detection instrument. When the escape is ≥5ppm, adjust the total flow rate of the spray gun and the ammonia injection position.

[0034] In step A, the urea solution storage tank 1 is made of 304 stainless steel and has a capacity designed for the denitrification needs of three boilers for five days (e.g., 40 m³). It is equipped with a breathing valve, a liquid level gauge, and a liquid level transmitter. Before transportation, the pipeline sealing (e.g., soapy water is used to detect leaks at flange connections), the urea concentration (20% ammonia water is diluted to 5%-10%), and the storage tank temperature (water spraying is required to cool the tank in summer to prevent pressure increase) must be checked. Transportation is carried out using a multi-stage centrifugal pump (3 in use and 1 in standby), with the outlet pressure stabilized at 0.8-1.0 MPa. A pressure sensor is provided for real-time monitoring, and the standby pump is automatically switched in the event of an abnormality. The pipeline adopts a corrosion-resistant design and is mixed with desalted water through a static mixer during transportation to ensure solution uniformity. A compressed air atomization system (pressure 0.5-0.8 MPa) is used to deliver the urea solution simultaneously to prevent spray gun clogging and enhance the atomization effect.

[0035] In step D, the dual-fluid spray gun 4 is dynamically adjusted in multiple dimensions: the compressed air pressure is adjusted according to the NOx concentration gradient: when NOx is greater than 400 mg / Nm³, the pressure rises to 0.8 MPa (enhanced atomization); when NOx is less than 200 mg / Nm³, the pressure drops to 0.5 MPa (energy-saving mode); the atomization angle is dynamically adjusted from 30° to 60° through a spherical joint to ensure that the coverage of the flue gas cross-section is greater than 90%; a peristaltic pump (pulsation rate <5%) and an electromagnetic flowmeter (accuracy level 0.5) are used for coordinated control, with a flow range of 80-200 L / h and a response time of <5 seconds; multi-stage injection is started under high-load conditions: the upper spray gun is opened first, and the lower spray gun is opened as a backup gradient.

[0036] In step E, the opening order of the spray gun groups is adjusted based on the escape distribution model (such as the Gaussian diffusion algorithm), and the spray guns in the area with lower oxygen content are activated first.

[0037] The control unit dynamically calculates the urea solution demand based on a multivariable collaborative control algorithm by collecting real-time data on inlet NOx concentration, outlet NOx concentration, ammonia slip concentration, flue gas volume, and oxygen content. Simultaneously, the control unit divides the boiler into 3-5 longitudinal temperature zones based on temperature detection data from the in-furnace thermocouples 5 installed at each spray gun. The spray gun activation strategy is dynamically adjusted according to the following rules: When the temperature in a zone is between 850°C and 1100°C and the NOx concentration in the corresponding area is above a set threshold, the spray gun in that zone is activated and 60-80% of the urea demand is allocated.

[0038] If the temperature difference between adjacent zones exceeds ±50°C, the spray gun position balancing module is activated, the dual-fluid spray gun 4 in the high-temperature zone is preferentially enabled and the dual-fluid spray gun 4 in the low-temperature zone is closed; when the ammonia escape concentration exceeds 3ppm, the total flow rate of the currently working spray gun is proportionally reduced by 10-30%, and the ammonia spray position is reallocated to the zone with an oxygen content ≥4%.

[0039] Integrate multiple parameters such as inlet / outlet NOx, ammonia slip, flue gas volume, oxygen content, etc. to build a closed-loop feedback regulation logic; clarify the relationship between the algorithm input variables (inlet / outlet concentration, etc.) and the output control quantity (urea demand); divide the temperature zone vertically (3-5 zones), and combine the data of thermocouples to achieve precise spatial control; set the temperature threshold (850-1100℃) and link it with the concentration threshold to ensure that the spray gun only operates in the effective reaction window.

[0040] The urea distribution ratio in each zone (60-80%) optimizes reaction efficiency and avoids local overspray. When the temperature difference exceeds the limit, the spray gun balancing module is triggered, giving priority to the high-temperature area to improve denitrification efficiency (refer to the optimal reaction temperature of SNCR). The ammonia escape concentration threshold is set (3ppm). When the limit is exceeded, the amount is reduced according to the gradient (10-30%) and the ammonia spraying position is moved to the high-oxygen area (≥4%) to inhibit the formation of ammonium bisulfate.

[0041] The above embodiments are only used to illustrate the technical method of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A boiler SNCR denitrification control system with automatic adjustment of ammonia injection, characterized in that: It includes a reducing agent supply unit, a multi-stage injection unit, a temperature monitoring network, a flue gas analysis and monitoring module and a control unit; The reducing agent supply unit is composed of a urea solution storage tank (1), a high-pressure delivery module (2), and a parallel filter branch (3), and the concentration of the urea solution is controlled within the range of 10-20%. The multi-stage injection unit comprises a plurality of layers of atomizing spray gun arrays arranged along the axial direction of the boiler flue, with a plurality of dual-fluid spray guns (4) provided on each layer, and the spray coverage area being ≥ 85% of the flue cross section; The temperature monitoring network is configured with a plurality of groups of thermocouples (5) mounted on the dual-fluid spray gun (4), with a sampling frequency of ≥3 times / second; The flue gas analysis and monitoring module includes several sets of NOx concentration detection instruments set inside the boiler to detect the inlet / outlet NOx concentration and ammonia escape in real time; The control unit includes a temperature field prediction module and a dynamic injection algorithm, and interacts with the DCS system data through the OPC protocol.

2. The boiler SNCR denitration control system with automatic adjustment of ammonia injection according to claim 1 is characterized in that: The high-pressure delivery module (2) comprises a high-pressure delivery pump and a urea solution delivery pipeline that sequentially connects the urea solution storage tank (1), the parallel filter branch (3) and the dual-fluid spray gun (4); The urea solution delivery pipeline is provided with an electric heating module, and the heating temperature is controlled at 40-60° C. to prevent urea crystals from clogging the pipeline.

3. The boiler SNCR denitration control system with automatic adjustment of ammonia injection according to claim 2 is characterized in that: The parallel filter branch (3) includes several stages of filter structures; The filtering structure includes a stainless steel filter screen and a self-cleaning device; The self-cleaning device adopts a backwash structure and uses a pressure difference sensor for real-time monitoring; When the pressure difference of the parallel filter branch (3) is ≥0.15 MPa, the backwash structure is started, and the flushing cycle is ≤10 minutes.

4. The boiler SNCR denitration control system with automatic adjustment of ammonia injection according to claim 3 is characterized in that: The compressed air pressure of the dual-fluid spray gun (4) is 0.35-0.45 MPa, the urea solution pressure is 0.18-0.22 MPa, the atomization angle is 60-90°, and the atomized particle size distribution D90 ≤ 50 μm; The thermocouple (5) is a K-type armored thermocouple or an S-type thermocouple, and the installation spacing of the thermocouple (5) is set to 0.8±0.2m from the front end of the dual-fluid spray gun (4), and the furnace temperature at the spray gun position is detected in real time, and the temperature detection range is 800-1100°C.

5. The boiler SNCR denitration control system with automatic adjustment of ammonia injection according to claim 4 is characterized in that: The temperature monitoring network includes dividing the boiler into a plurality of longitudinal temperature zones at different locations inside the boiler, and dynamically adjusting the zone range according to the SNCR optimal reaction temperature window; The dual-fluid spray gun (4) and the thermocouple (5) are installed at different longitudinal temperature zones to monitor the temperature gradient of the longitudinal section of the furnace in real time and dynamically adjust the spray gun flow rate according to the real-time temperature value.

6. The boiler SNCR denitration control system with automatic adjustment of ammonia injection according to claim 5 is characterized in that: The NOx concentration detection instrument is set 1-3 meters downstream of each dual-fluid spray gun (4), and the NOx concentration detection instrument is connected to the control unit to provide real-time feedback on the local denitrification efficiency; When the local denitrification efficiency is lower than 80%, the atomization pressure and injection angle of the corresponding dual-fluid spray gun (4) are adjusted first, and the coordinated compensation injection of the adjacent spray guns is triggered.

7. The boiler SNCR denitration control system with automatic adjustment of ammonia injection according to claim 6 is characterized in that: The temperature field prediction module adopts an LSTM neural network model, and its input parameters include boiler load rate, burnout damper opening, and calorific value of pulverized coal, and outputs a thermodynamic map of temperature distribution in the next 15 minutes.

8. The boiler SNCR denitration control system with automatic adjustment of ammonia injection according to claim 7 is characterized in that: The dynamic injection algorithm is based on the PID control principle and adopts an injection control strategy with a layered compensation mechanism and redundant injection logic; Layer compensation mechanism: when the temperature of a layer is lower than 860℃, the spray gun of that layer is turned off and the adjacent upper layer is activated; Redundant injection logic: When the outlet NOx concentration is greater than 50mg / m³, the standby spray gun group is activated and the compressed air pressure is automatically increased to 0.45MPa; The temperature field prediction module pushes the temperature field distribution tensor to the dynamic injection algorithm every 10 seconds as an input parameter for injection angle / depth adjustment; The dynamic injection algorithm feeds back the actual denitrification efficiency to the prediction module in real time for online fine-tuning of the LSTM model.

9. A boiler SNCR denitrification control method with automatic adjustment of ammonia injection, characterized in that: According to any one of claims 1 to 8, the SNCR denitration control system for boilers with automatic adjustment of ammonia injection comprises the following specific steps: Step A: transporting the urea solution in the urea solution storage tank (1) to the multi-stage injection unit; Step B: obtaining temperature data at the spray gun position by arranging a thermocouple (5) at the front end of the dual-fluid spray gun (4); Step C: Obtain the NOx concentration value in the flue gas in real time through the NOx concentration detection instrument and feed the value back to the control unit; Step D: The control unit dynamically adjusts the compressed air pressure, atomization angle and urea solution injection amount of the dual-fluid spray gun (4) according to the NOx concentration; Step E: Monitor the ammonia escape in real time using a NOx concentration detection instrument. When the escape is ≥5ppm, adjust the total flow rate of the spray gun and the ammonia injection position.

10. The method for controlling boiler SNCR denitration with automatic adjustment of ammonia injection according to claim 9, characterized in that: The control unit dynamically calculates the urea solution demand based on a multivariable collaborative control algorithm by collecting real-time data on inlet NOx concentration, outlet NOx concentration, ammonia slip concentration, flue gas volume, and oxygen content; When the temperature of a certain zone is between 850-1100℃ and the NOx concentration in the corresponding area is higher than the set threshold, the zone spray gun is activated and 60-80% of the urea demand is distributed; If the temperature difference between adjacent zones exceeds ±50°C, the spray gun position balancing module is activated, the dual-fluid spray gun (4) in the high-temperature zone is preferentially activated, and the dual-fluid spray gun (4) in the low-temperature zone is closed; When the ammonia escape concentration exceeds 3ppm, the total flow rate of the currently working spray gun is proportionally reduced by 10-30%, and the ammonia spray position is reallocated to the partition with oxygen content ≥4%.

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